Nonwoven fabric

Abstract

A nonwoven fabric characterized in that it contains: 1) a fiber comprising a copolymer of propylene and ethylene; and 2) a fiber comprising a polypropylene homopolymer is disclosed.

We claim: 
     
       1. A nonwoven fabric comprising: (1) a fiber comprising a copolymer of propylene and ethylene; and   (2) a fiber comprising a propylene homopolymer;   wherein the fabric is surface bonded and when welded to itself has a delamination strength of at least 5 kg, as measured on a 10 cm wide sample strip with an Instron tester at a test speed of 50 mm/min.   
     
     
       2. A nonwoven fabric according to claim 1 wherein fiber (1) comprises a blend of a copolymer of propylene and ethylene and polypropylene homopolymer. 
     
     
       3. A nonwoven fabric according to claim 1 wherein the copolymer of propylene and ethylene contains up to 5% by weight ethylene. 
     
     
       4. A nonwoven fabric according to claim 2 wherein the blend comprises 1 to 99% by weight copolymer. 
     
     
       5. A nonwoven fabric according to claim 1 wherein the copolymer of fiber (1) has a melting point between 125° and 165° C. and the homopolymer of fiber (2) has a melting point between 160° and 170° C. 
     
     
       6. A nonwoven fabric according to claim 1 wherein the copolymer of fiber (1) has a melt flow index of 1 to 20 and a molecular weight distribution of 3 to 6. 
     
     
       7. A nonwoven fabric according to claim 1 wherein the homopolymer of fiber (2) has a melt flow index of 3 to 40 and a molecular weight distribution of 3 to 6. 
     
     
       8. A nonwoven fabric according to claim 1 wherein fiber (1) and fiber (2) are mechanically drawn. 
     
     
       9. A nonwoven fabric according to claim 1 wherein fiber (2) is mechanically drawn and fiber (1) is not mechanically drawn. 
     
     
       10. A nonwoven fabric according to claim 8 wherein the fiber (1) and (2) are drawn at a mechanical drawing ratio between 1 and 3. 
     
     
       11. A nonwoven fabric according to claim 1 being composed of two or more layers wherein at least one layer comprises fiber (1) and at least one layer comprises fiber (2). 
     
     
       12. A nonwoven fabric according to claim 11 being composed of three or more layers wherein the outer layers comprise fiber (1). 
     
     
       13. A nonwoven fabric according to claim 11 wherein one or more layers comprised of fiber (1) are melted to form a film by additional calendering methods. 
     
     
       14. A nonwoven fabric according to claim 9 wherein fiber (2) is drawn at a mechanical drawing ratio between 1 and 3. 
     
     
       15. A nonwoven fabric comprising: a fiber (1) that is a copolymer of propylene and ethylene, and a fiber (2) that is a polypropylene homopolymer;   said nonwoven fabric having a first fiber layer and a second fiber layer;   said first fiber layer consisting essentially of a blend of a fiber (1) and a fiber (2), said first layer comprised of 10% to 90% by weight of fiber (1) and of 10% to 90% by weight of fiber (2);   said second fiber layer consisting essentially of said fiber (2);   the fibers of said first and second fabric layer being surface bonded to achieve a delamination strength of at least 5 kg, as measured on a 10 cm wide sample strip with an Instron tester at a test speed of 50 mm/min.   
     
     
       16. A nonwoven fabric according to claim 15 wherein fiber (1) has a denier of between 3 and 10 dpf and fiber (2) has a denier of between 8 and 22 dpf. 
     
     
       17. A nonwoven fabric according to 16 wherein fiber (2) has a denier that is at least 2 dpf greater than the denier of fiber (1). 
     
     
       18. A nonwoven fabric according to claim 17 wherein said fabric is calendered and has a Gurley porosity, measured according to ISO 5636/5, of more than 5 seconds. 
     
     
       19. A nonwoven fabric according to claim 15 wherein said fabric is further comprised of a third fabric layer, said third fabric layer consisting essentially of a blend of a fiber (1) and a fiber (2), said third layer comprised of 10% to 90% by weight of fiber (1) and of 10% to 90% by weight of fiber (2).